Variation Analysis And Clinical Significance Of Synovial Fluid With Hip And Knee Periprosthetic Joint Infection

Objective:To analyze the variation of joint fluid index and its application value in predicting the postoperative efficacy and reinfection of patients with periprosthetic infection.Methods : The data of 85 patients who underwent artificial joint revision surgery due to infection around hip and knee prostheses in our hospital from January2019 to March 2022 were retrospectively analyzed.The trend of joint fluid index was analyzed as a whole.According to whether there was a second peak in the overall trend,they were divided into two groups: the group with the second peak(Group Y)and the group without the second peak(Group N),and then divided into the hip joint group(Group hip)and the knee joint group(Group knee)according to the different infection sites.There were 41 patients in group Y,including 21 males and 20 females,with an average age of 61.18±8.79 years;There were 44 cases in group N,including 18 males and26 females,with an average age of 62.00±9.37 years.There were 36 cases in the hip group,including 19 males and 17 females,with an average age of 60.50 ± 8.98 years;There were 49 patients in the knee group,20 males and 29 females,with an average age of62.67 ± 9.37 years.According to the comparison of whether there is a second peak change and the difference between the white blood cell count(WBC)and the proportion of polymorphonuclear leukocyte(PMN%)in the joint fluid,the decline rate of WBC in the joint fluid(WBC＿ROD),the last joint fluid white blood cell count(LWBC),the decline rate of polymorphonuclear leukocyte(PMN＿ROD),and the last polymorphonuclear leukocyte(LPMN%)in the joint fluid,Analyze the relevant risk factors of the second peak and different infection sites,and finally draw the working characteristic(ROC)curve of the subjects and the prediction of the above indicators on the efficacy of PJI and reinfection.Results:After overall analysis,the WBC of joint fluid in 80.00% of cases showed a downward trend,and that in 20.00% of cases showed an upward trend.The WBC of joint fluid decreased significantly on the fifth day after operation.The PMN% of 91.76% cases showed a downward trend,and the PMN% of7.06% cases showed an upward trend.The overall PMN% showed a single phase attenuation trend after surgery.WBC and PMN% of joint fluid were analyzed according to whether there was a second peak.There were statistically significant differences in WBC of joint fluid between Group Y and Group N on the 5-15 days after operation(P<0.05)＿The difference of ROD was statistically significant(P=0.008);The difference of PMN%on the 3rd and 9-15 days after operation was statistically significant(P<0.05)＿The difference between ROD groups was statistically significant(P<0.0001).After the logistic regression analysis of the baseline data of patients in Group Y and Group N,it was found that gender,age,infection site,bacterial culture and drainage tube retention time were not the risk factors for the second peak(P>0.05).After drawing ROC curve,The AUC values of WBC＿ROD and the last joint fluid WBC(LWBC)were 0.334 and 0.741,respectively,The AUC values of PMN＿ROD and PMN%(LPMN%)were 0.253 and0.661 respectively.The last joint fluid index has a high predictive value for the second peak.WBC and PMN% of synovial fluid were analyzed by grouping according to the infection site.Only on the 15 th day after operation,WBC of synovial fluid in group Y and group N had statistically significant difference(P=0.037).WBC＿There was no significant difference in ROD(P=0.997);There was no statistically significant difference in PMN% 15 days after operation(P>0.05),PMN＿There was no statistically significant difference between ROD groups(P=0.456).Logistic regression analysis of baseline data of patients in Group Y and Group N found that gender,age,bacterial culture,and indwelling time of drainage tube were not risk factors for infection site(P>0.05).After drawing ROC curve,The AUC values of WBC＿ROD and the last joint fluid WBC(LWBC)were 0.499 and 0.436,respectively,The AUC values of PMN＿ROD and the last PMN%(LPMN%)were 0.556 and 0.445 respectively.The predictive value of the above indicators for the infection site is low.Conclusion:The indexes of joint fluid showed a downward trend after surgery,but the value of evaluating the efficacy of PJI alone and predicting reinfection within 15 days after surgery was not high.